The present invention relates to subterranean treatment fluids and additives that may be useful in subterranean treatments and oil recovery operations, and more specifically, to certain reversible surfactants, treatment fluids, and methods of use employing such reversible surfactants.
Treatment fluids may be used in a variety of subterranean treatments, including, but not limited to, stimulation treatments and sand control treatments. As used herein, the term “treatment,” or “treating,” refers to any subterranean operation that uses a fluid in conjunction with a desired function and/or for a desired purpose. The terms “treatment,” and “treating,” as used herein, do not imply any particular action by the fluid or any particular component thereof. Examples of common subterranean treatments include, but are not limited to, drilling operations, pre-pad treatments, fracturing operations, perforation operations, preflush treatments, afterflush treatments, sand control treatments (e.g., gravel packing), acidizing treatments (e.g., matrix acidizing or fracture acidizing), “frac-pack” treatments, cementing treatments, and well bore clean-out treatments. In these subterranean treatments, surfactants may be included in a treatment fluid for a number of purposes such as an emulsifying agent, a non-emulsifying agent, a foaming agent, a defoaming agent, a viscosifying (or gelling) agent, a dispersant, a wetting agent, and the like.
While a variety of surfactants have been used in subterranean operations, various problems have been associated with their use. For instance, certain surfactants used heretofore may have undesirable environmental characteristics and/or may be limited by strict environmental regulations in certain areas of the world. As a result, use of these surfactants in subterranean operations may result in the potential for the bioaccumulation and/or persistence of such surfactants in the environment, which may create potential dangers for their use, such as adverse effects on shrimp and other aquatic species. Additionally, in the course of using a surfactant, it may be desirable for the fluid to exhibit the properties that the surfactant imparts only after an initial period of time (e.g., delayed foaming or emulsifying of a fluid), or to “turn off” the surfactant after some period of time (e.g., defoaming or de-emulsifying of a fluid).
In order to control the surface activity or rheological properties imparted to a fluid, certain surfactants containing degradable groups, such as ester-based surfactants, amide-based surfactants, and acetal-based surfactants have been employed in the art. For example, certain of these surfactants may degrade or become otherwise altered (e.g., “cleaved” into pieces) after a certain period of time or under appropriate conditions (e.g., temperature, pH, oxidizers, aqueous environment, etc.), resulting in cessation of the surface active or rheological properties that those surfactants impart to a fluid. However, these degradation and cleaving processes for certain surfactants (e.g., amide surfactants) may require long periods of time or reactants or conditions (e.g., acidic pH, high temperature, etc.) that may be difficult to obtain in a subterranean environment. Moreover, once these surfactants have been degraded or cleaved, generally they are unsuitable for subsequent use.